-
White tigers are very hard to find in the wild. In about 100
years, only 12 have been seen in the wild in India
- The first known White Tiger
was captured in the jungles of Rewa in 1951, by the Maharaja
of Rewa
- The White Tiger has pale icy blue
eyes, white fur with dark stripes, pink nose and pink paw
pads
- The White Tiger IS NOT an albino
- Golden offspring that carry the
white gene are called Heterozygous
- Most White Tigers are Bengals,
although some are Bengal - Siberian crosses
Tigers are an Asian species, found from the frozen tundra
of the Soviet Far East, south to the humid jungles of Malaya
and Indonesia, and west to the hot, hardwood forests of India.
There are five living subspecies; three others are already
extinct. Current estimates put the world population of wild
tigers at about 5,000-7,000, the most numerous race being the
Bengal race, distributed among some 18 tiger reserves and
sanctuaries of India (and a half-dozen in Nepal and
Bangladesh), accounting for over two-thirds of all wild tigers.
Every once in a great while, a white tiger appears in the
wild. White tigers differ from ordinary orange tigers (if a
tiger can be referred to as ordinary) in having ice-blue eyes,
a pink nose, and creamy white fur with chocolate stripes. White
tigers are not albinos; their color is caused by a double
recessive allele. A Bengal tiger with two normal alleles or one
normal and one white allele is colored orange. Only a double
dose of the mutant allele results in white tigers.
How frequently do white tigers appear in nature? No one
knows. But we do know that in the last 100 years, only about a
dozen such white tigers have been seen in India (white forms
have never been reported for any of the other subspecies).
During this same century, the Bengal tiger population has
dropped from 40,000 to a low of 1,800 tigers, and approximately
100,000 have lived and died, suggesting that as few as one in
every 10,000 tigers is white.
The white tiger collection in North American zoos traces
its ancestry to a single white male known as Mohan, captured in
1951 in central India. It did not take long for the Maharajah
who captured him to figure out that the only way to produce
additional white tiger cubs was to breed Mohan back to his
daughter, who gave birth to the first generation of
captive-born white tigers in this century. One of these
granddaughters, Mohini, was bred with her uncle and
half-brother, an orange male called Sampson. It was through
Mohini that the white tiger line came to the United States
through the National Zoo in Washington D.C., From there, two of
Mohini's offspring, a brother and sister, were bred at the
Cincinnati Zoo and their daughter, Kesari, founded the
Cincinnati white tiger line.
In Cincinnati, the inbreeding continued. Bhim, a white son
of Kesari, was mated to his sisters Kamala and Sumita, and so
on. Altogether, the average inbreeding coefficient of the white
tiger lineage is much higher that that of either Sumatran of
Siberian tigers managed by the tiger SSP which is methodically
working towards minimizing the average inbreeding coefficient
of its captive population. This translates into a healthier
population and decreases the probability of a number of
reproductive and disease problems associated with inbreeding.
An SSP is a breeding strategy followed by participating
zoos that is designed to maintain small self-sustaining
populations of endangered species in captivity. Every breeding
recommendation is designed to minimize the average inbreeding
coefficient of the population and to equalize the genetic
representation of each wild-caught animal ("founders" of the
captive population). With some 63 such species blueprints in
hand, zoos are increasingly becoming last-ditch refuges for
endangered species, as a kind of biological (rather than
biblical) Noah's ark. Already on board are several species now
extinct in the wild that survive only in zoos, including Pere
David's deer and Asian wild horses, and three additional
species, the California condor, Arabian oryx, and black-footed
ferret, are currently making their way back into the wild
thanks to captive breeding.
by Ronald L. Tilson
Coordinator, CBSG Tiger Global Conservation
Strategy (GCS)
These exerts originally appeared in a Commentary in Zoo
Biology (11:71-73, 1992).
|